It's time to take the LG5 3.1 Turbo V6 powerplant to the next step. The Buick Grand National guys can make their low-tech 3.8L 90* V6 run 10s as standard-fare, so I see no reason we can't make our 3.1 60* V6s run at least 13s with a standard recipe. We have done the small bolt ons like chip, air filter, and exhaust, and it provided some small noticable gains. But surely there is a group of enthusiasts/owners out there more serious about performance and ready to step up to the next level. I figure the small bolt on stage brings us to about 250-275 HP and 300 LB-FT. But I am interested in the 350-400HP range. I think it will be much more simple to accomplish than the routes people are currently going. I see people putting heads, cams, and doing port work while still maintaining the stock T25 turbo or upgrading to the T28. I think that's all wrong. I think it will only require the following things. 1.) Increased boost on stock motor. 2.) Additional fuel since the paltry stock 22# injectors are maxxed out with a Top Gun chip, 3.) high performance transmission rebuild to handle the power, 4.) Traction (?), and 5.) High octane fuel to allow running high boost and timing. It's very tough to make good power on 93 octane pump gas on a stock motor. In fact according to
http://www.sdsefi.com/techcomb.htm, "
turbo engines cannot realize their full hp potential without high octane fuel.".
http://www.sdsefi.com/techocta.htm is also good relevant reading on this subject.
The first thing to upgrade after the initial "small bolt on stage" would be the woefully inadequate stock T25 turbo. It can't even put out enough boost efficiently, to reach the limit of 93 octane. That's really weak!! I'm accustomed to turbo vehicles coming with turbos large enough that you can turn the boost high enough to reach the limit of high octane racing fuel. I beleive if you take the stock LG5 motor on a TGP, put a more suitable ~500cfm turbo on, and run 20 PSI Boost on high octane fuel, it would be in our 350-400 HP range and solid 13s, maybe even low 13s or better. That's considering our crippling FWD traction issue.
But before you can run 20 PSI boost you need the turbo, like I was saying. There doesn't seem to be ANY good options here. The T28 is a negligible upgrade as far as I'm concerned. It still has the incredibly tiny T25 turbine orifice and would use that horrible stock crossover T2 exhaust flange. Most of the T28s I've seen advertised said it was good for 300HP. $1000 to run 3 tenths (30HP) faster doesn't sound like good bang for the buck as far as my wallet is concerned! The best option I've seen so far is Jud's ball bearing $975 "GT28" turbo and even that looks too small. What I'd like to see is a T3-flanged crossover pipe. Then I could bolt on my stock Syclone turbo (Mitsubishi TD06-17c, 8cm2 exhaust housing, internal wastegate, water/oil cooled, and 550cfm. Maximum efficient output behind a 4.3L 262cid V6 engine is 20 PSI which is certainly more than enough for us. Maybe a little too big. FWIW, 20 PSI on the cited 4.3 engine resulted in approximately 410HP and 12.2 @ 108 MPH quarter mile times completely maxxed out stock combo with Perfect traction coming out of the hole hard enough for 1.7 60's. Very similar weight vehicle to a TGP.)
With a T3 turbo our turbo SIZE problem would no longer be an issue as there are lots of selections there, the Ford Turbo 2.3 4 cylinder turbo, a Garret T3 (not sure on exact specs) would be a good size for the 300-350 HP range. However, our next issue would be mating a downpipe. The TGP uses a T2-specific 5-bolt pattern that I don't beleive any T3-family uses. Even Jud's "GT28" turbo required a little cut-n-fit to make it work. However the pipe from the turbo to the catalytic converter area is not very complicated so I assume a custom downpipe could be made relatively easily, so long as it had some type of heat wrapping to keep out bastard WalletMaster III brake system from frying of heat. Our stock T25 also has a highly unusual O2 sensor bung cast directly in the exhaust housing (How non-standard could they get? It's almost like ASC/McLaren went out of their way to make upgrading this thing really miserable.) So installing a new O2 sensor bung post-turbo will also be necessary.
Let's assume we got the bigger T3 turbo with an internal wastegate, and a new crossover pipe with a T3 flange, and got a downpipe to mate and complete the exhaust. (Stock 2.25" exhaust should be sufficient for everyone, I went 12.2 @ 108 with my Syclone's stock 2.5" downpipe so unless you plan on going faster than that I don't believe 3" is necessary. I also ran an open dump on my TGP and noted virtually no HP/TQ increases over full exhaust with no cat.). Anyways, the next thing you'll need to do is find a way to plumb the turbo's oil and water lines. No small task given the tight space restrictions of our FWD engine bay. Jud seems to have it figured out with his GT28 but keep in mind how costly those blue and red aluminum -AN connectors are. Expect to spend at least $100 here with lots of time hand cutting, hand assembling, and fitting.
Next order of business will be the fuel. Like I said the stock 22# injectors belong on a naturally aspirated V6, not a Turbo V6. We have the option of using larger injectors (I'd say the SyTy 28# stock injectors would be suitable and surely available cheap in used form from SyTy people upgrading, for the $50-$100 range.) Adding more injector would allow us to run more boost but KEEP IN MIND that adding more fuel does NOT increase the point of detonation for a given fuel. So let's say on a stock TGP motor with 8.8:1 compression and aluminum splayed-valve heads with a nice heart-shaped combustion chamber, you can run 12 PSI Boost maximum with 0 detonation before the stock T25 turbo runs out of steam (and goes SLOWER at any subsequent increase in boost past 12 PSI). With larger injectors you may realize the true limit of 93 octane gas is really only 15-16 PSI. 3 PSI isn't
that much more over 12 PSI. Once you reach the boost limit of your fuel (octane),
more fuel isn't going to change that octane rating. I see that point frequently misunderstood. After the octane limit of 93 is reached, to continue increasing the boost (and power) you must step up to high octane fuel (or build a motor that flows more air i.e. build it like a N/A motor by doing stroker crank/rods, ported heads, cam, etc. [engine internals]). As we learned from the SDSEFI Tech Page link (see above), a turbo engine is going to reach its maximum horsepower potential only on high octane fuel. What that means for us, is if we want to really go fast on our stock motors, we need to run high boost and high octane fuel. I have done this successfully for 3 years on my stock motor Syclone. I have over 1000 quarter mile passes and its currently running 11.7s @ 114mph with 23 PSI Boost and I have never had to remove a valve cover because I am careful. Now am I suggesting this is for everyone? Absolutely not, some people only can handle stomping their right foot or showing off in front of friends, that is not going to allow your motor to last, you must have self control and the willpower to play it safe and monitor your motor to ensure it is never detonating (pinging) or it will self destruct in short order at these types of high boost, high-HP levels. But for those willing to step up, we can run Wideband O2s and/or scan tools to datalog our knock sensors and ECM values to monitor what is happening, and slowly and carefully turn up the boost until maximum power output is reached in a safe manner.
So I was discussing adding extra fuel. If you change injectors to a size large enough to handle our target power output, they will be of a size large enough over stock to the point where a chip calibrated for stock 22# injectors will not drive properly doing the upgraded injectors. I know people like to ignore this fact but I beleive it to just be the hard truth. This is another serious void that needs to be filled before us as LG5 tuners can really start to enjoy some significant power output. As far as I know there are NO proper street-car chips for larger injectors. I mean chips that perform properly at WOT as well as driving in stop and go traffic, in cold weather, in warm weather, etc. However, there is 1 alternative to adding bigger injectors that I haven't mentioned up till now, and it is the method I may be using. One could keep the stock injectors and run them static (at 100% output, however insufficient it may be at WOT) and then supplement the fuel with alcohol injection. I do this on my Syclone and it performs beyond my wildest expectations. Specifically I use the SMC (
www.smcenterprises.com) $400 alcohol injection kit and I spray Methanol which is, according to my research, the second best race fuel only to Nitromethane. Originally I heard people say "alcohol injection is almost as good as race gas." but this seems to be only half true. It may actually be
better than race gas! Methanol has 10% oxygen content so as it burns, it's like a slight nitrous oxide effect. Also it releases slightly less heat (BTUs) than gasoline BUT it burns at a much richer AFR (air fuel ratio) so in the end it does release more heat than gasoline and will create higher PCP pressing the piston down harder and creating more power. Ever see 7 second "alcohol dragsters"? There is a reason they are running Methanol and not gasoline anymore. (Same reason all the 4 second cars are running Nitromethane). Back to methanol. Spraying methanol in the intake also has a TREMENDOUS intercooling effect, to the point where it can make the intake manifold have condensation form on it like the outside of a beer can on a warm day (I have felt it with my own hands.) I have also datalogged intake manifold temperatures while spraying methanol, that are 10*F LOWER than the actual air temperature outside. (I.e., I tested on a 35*F day and I got my intake manifold temperature sensor to read 25*F.) Finally the methanol obviously provides additional fuel so I beleive I could do the same thing on my TGP as I did on my Syclone -- that is, max out the stock fuel injectors but spray Methanol injection at WOT for extra fuel that is also high octane AND cooling the combustion chamber, for a result that nets me not only increased total fuel quantity but also quality (octane) and provides dramatic intercooling to the point where a stock intercooler upgrade is not necessary.
Now I realize our stock TGP intercooler does really suck, being completely blocked of direct air flow (unless you hack your air conditioner), but at this point I think there is insufficient data to suggest replacing it. I will wait until after all the prior things I have mentioned have been installed and see if the intake manifold temperatures truly suggest an intercooler deficiency at the top end of the dragstrip.
There is one last thing to mention regarding our fueling. I did say there is no chip available to handle larger injectors. But I also need to mention there is ALSO no chip available that can add fuel over 15 PSI! Our ECM is speed-density which means it uses the MAP sensor to determine the current engine air flow (as opposed to a MAF (Mass air Flow meter)). However our stock MAP sensor is only 2-BAR. Meaning it can read 1 BAR of vacuum, and 1 BAR of boost. In other words after 14.7 PSI (1 BAR) Boost, the ECM is flying blind and doesn't have any idea if you are at 16 PSI or 25 PSI and it can't possibly add the respective amount of additional fuel. GM made a 3 BAR MAP sensor for the boost gauge on the MAF-equipped 1989 Turbo Trans Am which had a 16.5-PSI stock boost level, but it's not as simple as plugging in the MAP sensor into your TGP and running. Your chip has to be TOTALLY recalibrated to read the 3 BAR MAP sensor AND custom Motorola assembly code would need to be implemented. As far as I know, there is only 1 person to have accomplished this and it was Brian Green only for the '749 Syclone/Typhoon/TurboSunbird/GrandAm/Calais/Quad4 ECM. This is one of the most difficult barriers we will need to surpass. The Buick 3.8 Turbo V6 motor doesn't have this issue because it uses Mass Air. The modified Syclone/Typhoons all run 3-Bar MAP and 3-Bar chip as some of the first bolt-ons, and there aren't really any other Speed-density (MAP) turbo GM motors out there that people are modifying other than the ones I've listed. The way I plan on addressing this problem is most likely to use a fuel-cut-defeater and alcohol injection on stock injectors, which is a very crude and imprecise fueling system, but it has performed very well on my Syclone probably partially due to the forgiveness of Methanol's 4:1 Air-fuel ratio (in other words even if you have a bunch of extra methanol, it isn't really going to effect power output in a negative way like running much too rich on gasoline would.) I also plan on using a wideband O2 to accurately sample the air fuel ratio and determine if I'm going lean (stock O2 is not sufficient!!)
www.plxdevices.com sells a nice one for under $300 using the newly discovered cheap Bosch Wideband O2 sensor (the old NTK sensor alone was over $150!)
So anyways I believe the formula of high boost and high octane is a pretty time tested one for making high power output on a turbocharged motor. I will assume that at 17-20 PSI with a big turbo and sufficient fuel (100-110+ octane on larger injectors, or the combo of stock injectors with 93 octane and Methanol injection), we will make the targer HP. The only remaining problems are transmissions and traction. Once again we are bitten because this path has hardly been beaten down before. So there is little if any transmission failure research/analysis to provide us with a source for upgraded, stronger, intelligent 4T60 upgrades to handle the 400+ LB-FT of torque we may be putting out. Our tranny is not easily removed/reinstalled either (is it?) So this is a critical factor currently limiting our success. I am for the record, not a fan of 5 speeds for drag racing (but definitely for autocross/road-racing) and I don't think a 5 speed letting off the gas 3 times going down the track is going to be as fast as a properly built (i.e. quick shifting) automatic that gets 100% WOT from start to finish AND can spool up the bigger turbo at the line with brake-torqueing.
Finally let's assume we had the motor putting out the power, and the tranny able to handle it. The last problem is getting traction and I think this will always cause us to suffer 3-5 tenths over someone with RWD or AWD but anyone who is modifying their Grand Prix will have had to acknowledge this irreversible fact at the start of their project so it should come as no surprise.
I am hoping for lots of input on this subject and maybe we can start to really show people what this extremely oddball, one-off Turbo V6 GM motor can do. So in summary, here are the issues remaining that we need to solve:
1.)
2.) [ ] Need T3 style exhaust crossover flange
3.) [ ] Need T3 adaptable downpipe flange
4.)
5.)
- Need turbo oil/water plumbing to fit new turbo
6.) [ ] Need 3-Bar MAP sensor and respective 3-Bar programmed chip code
7.)
8.)
- Need wideband O2 to safely run high boost
9.) [ ] Need 4T60 automatic transmission parts sufficient to handle the power
10.) [ ] Need traction to utilize increased power.
* Problems marked
- have readily-available solutions. Problems without an
- are currently unsolved and keeping the TGPs by far and large in the 14s!!
The Future: I dont think camshafts or heads or porting or throttle bodies or any of those things are necessary until after the level I've discussed has been reached. So I will not discuss them and I will assume they are NOT part of our equation as they could really throw it off. (High flowing heads or a high lift cam are certainly going to throw your chip calibration off wack and far from optimal, and besides that, I am not convinced the extra airflow is not gonna do you much good on a stock turbo when its already severely bottlenecked from the factory with the stock crossover exhaust flange and turbine housing.)
I do have one other comment I want to add that I forgot to fit in above; I'm pretty disappointed that it will take so much time, effort (cutting/fitting/customizing), and money $$$ to go to the next level. Most of this is because the stock turbo is so non-upgradeable and because our cars are so obscure and one-off that there is virtually zero aftermarket. But no sense crying over facts that cannot be changed, so let's forge ahead!
